Evolution, ecology and genomics of the Great Lakes invader, the red algal species Bangia atropurpurea.

红藻(红藻)在化石记录中是一个古老的谱系，可以追溯到1.2Ga和1.7Ga；这两个化石都推迟了真核生物多细胞进化和有性繁殖的进化。此外，红藻是地球上含有初级叶绿体的光合作用生命演化中的关键类群，也通过第二和第三级内共生作用将叶绿体贡献给其他真核物种。尽管这个类群的重要性显而易见，但人们对许多红藻谱系的了解仍然很少，特别是该门中更多的基础类群。直到最近，基因组测序才被用于研究这一门的成员，并注意到红藻和其他真核生物之间的差异，以及独特的逆境耐受性。在这项提案中，我们的目标是对紫毛班加物种的基因组和选定的转录本进行测序。这项研究提案将是第一次对严格意义上的淡水红藻物种的基因组进行排序，该物种也是劳伦斯五大湖的入侵者。值得注意的是，班加红藻是红藻中唯一一个只在淡水(不咸)和其他海洋环境中有物种的属，也是唯一被证明在实验中从海洋过渡到淡水或从淡水过渡到淡水的红藻。因此，该属是研究渗透胁迫引起的转录变化的一个很好的模式生物，我们将能够识别参与驯化和渗透胁迫过程的基因，并预测控制入侵新栖息地的界限。此外，1.2Ga的红藻化石在形态上与班加很难区分，因此是分类上最古老的真核生物化石。该化石提供了真核生物化石记录中第一个有性繁殖的证据，因此，该属是研究有性繁殖进化以及生活史不同阶段基因表达的理想物种。众所周知，红毛竹只能无性繁殖，这种特殊的繁殖方式使它成为新栖息地的有效入侵者。

The red algae (Rhodophyta) are an ancient lineage in the fossil record dating 1.2 and 1.7 Ga; both of these fossils have pushed back the evolution of multicellularity in eukaryotes and the evolution of sexual reproduction. Furthermore, the red algae are a critical group in the evolution of photosynthetic life on earth containing primary chloroplasts and have also contributed chloroplasts through secondary and tertiary endosymbiosis to other eukaryotic lineages. Despite the obvious importance of this group, little is still known about many red algal lineages, in particular, the more basal classes within the phylum. Only recently, has genomic sequencing been used to examine members of this phylum and have noted differences among the red algae and other eukaryotes, as well as unique stress tolerances. In this proposal, we aim to sequence the genome and selected transcriptomes of the species Bangia atropurpurea. This research proposal would be the first to sequence the genome of a strictly freshwater red algal species, and this species is also an invader in the Laurentian Great Lakes. It is important to note that Bangia is the only genus in the red algae to have a species solely in freshwater (not brackish) and others in the marine environment and it is the only red alga to have been shown to experimentally transition from marine to freshwater or vice versa. Hence, this genus is an excellent model organism to examine transcriptomic changes due to osmotic stress and we will be able to identify genes that are involved in the process of acclimation and osmotic stress and predict the limits that control invasion into new habitats. In addition, the 1.2 Ga red algal fossil is morphologically indistinguishable from Bangia and hence is the oldest taxonomically resolved eukaryote fossil. This fossil provided the first evidence for sexual reproduction in the fossil record for eukaryotes and as a result, this genus is ideal to study the evolution of sexual reproduction as well as the expression of genes in different stages of the life history. Bangia atropurpurea is known to only reproduce asexually, and this particulary mode of reproduction enables it to be an effective invader into new habitats.